Texture mapping is a method for adding detail, surface texture or color to a computer-generated image (CGI). A texture map is applied (mapped) to the surface of a shape or polygon. This process is similar to applying patterned paper to a plain white box.
Virtual texturing refers to a texturing method in which the physical memory pool available for texture storage is less than the total amount of texture that is potentially useable to produce a CGI. When rendering using a virtual texture, typically only portions of the virtual texture or lower-detail versions thereof are made available to an active texture pool for rendering.